This is a core facility designed to (1) establish cell lines and extract nucleic acids from clinical material and (2) perform molecular genotype analysis. The core will support Project 3 (Mapping of the Cyclic Hematopoiesis Gene) and Project 4( Mapping of the Familial Leukemia Gene). For Project 3, this unit will process venous blood and bone marrow specimens and will be responsible for additional genotype analysis of the region first identified in family 619. For Project 4, this core facility will prepare immortalized lymphoblastoid cell lines from members of leukemia families and store aliquots of frozen bone marrow. DNA will be extracted and used in genotype analysis. RNA will also be prepared when needed for mutational analysis.